Disposable wet wipes products are manufactured and sold for personal cleansing needs in circumstances where a source of water, soap and cleaning cloth may be desired but are unavailable or inconvenient. An example of a wet wipes product is PAMPERS brand baby wipes, manufactured and sold by The Procter & Gamble Company for use in cleaning a baby's skin during a diaper change. The product includes a stacked supply of wipes formed of a suitable fibrous web structure pre-cut into individual sheets, and moistened with a suitable lotion formula. The lotion formula may be aqueous and may contain a variety of ingredients selected to aid in skin cleansing and to provide other benefits. The moistened supply of wipes is typically packaged in a rigid dispensing tub or dispensing package of flexible film, designed to effectively retain the moisture in the lotion after package opening, for the period of time expected for use of the entire supply. Wet wipes products are also manufactured and sold for other skin cleansing needs.
To be suitable for making a wet wipes product, the fibrous web structure should be capable of retaining a certain amount of structural integrity when wetted, i.e., it should not disintegrate like a typical cellulose pulp fiber-based material when wetted (like, e.g., typical rolled bathroom tissue products), and it should have a relatively soft feel. For these reasons, substrates used to make wet wipes products have often been formed largely of synthetic polymer components and structures that do not dissolve or disintegrate in water. Although such substrates desirably retain structural integrity and feel soft when wetted, they tend to be less absorbent and have relatively low-friction surface properties that render them less desirable as cleaning media (e.g., they may be more slippery and less likely to pick up soil), than cellulose fiber-based substrates.
Recently, hybrid “coform” substrates formed of blends of cellulose pulp fibers and synthetic polymer fibers have been used to make wet wipes products. Due to their naturally greater hydrophilicity, and to the greater coefficient of friction and surface texture they impart, the pulp fibers impart desirable absorbency properties and surface cleaning abilities to the fibrous web structure. The polymer fibers (together with other features added in processing) can help impart wet structural integrity.
More recently, improvements have been introduced to the co-forming process and resulting fibrous web structure. As described in U.S. application Ser. No. 13/076,492, a co-formed fibrous web structure with improved absorption properties is described. In addition to the other improvements described in that application, it is briefly surmised that layers formed of meltblown polymer filaments alone can be formed on the outermost surfaces of the co-formed batt prior to bonding, to beneficial effect. It is surmised that the addition of the meltblown layer (called “scrim”) can help reduce release of lint (comprising fibers dislodged from the structure) during use by a consumer.
However, the ways in which inclusion of scrim layers, and the relative proportions of components of the scrim layers and intermediate or core layers, affect properties such as tensile strength, drape, surface friction, opacity, texture and feel of the web material, have not been apparent or predictable. Thus, it would be beneficial if the best proportions of components overall, together with their allocations among the various layers or substructures, of a fibrous web structure having scrim layers, for use as wet wipe, could be identified. Further, although adding scrim layers to a co-formed structure can enhance some properties of the structure, to some consumers the scrim layers may reduce a desired perception of surface friction or roughness they may associate with cleaning efficacy, attributable to the presence of exposed pulp fibers at the surface.
Thus, there remains room for improvements in wet wipes substrates that incorporate the advantages of the hybrid pulp and polymer combination, while improving mechanical strength, reducing incidence of shedding/dislodgement of pulp fibers, and providing other improvements that may be beneficial.